Artist's Conception of the Heliospheric Current Sheet

The heliospheric current sheet separates regions of the solar wind
where the magnetic field points toward or away from the Sun. The
complex field structure in the photosphere simplifies with increasing
height in the corona until a single line separates the two polarities
at about 2.5 solar radii. That line is drawn out by the radially
accelerating solar wind to form a surface similar to the one shown in
this idealized picture. The surface is curved because
the underlying magnetic pattern rotates every 27 days with the Sun.

It would take about 3 weeks for material near the current sheet
traveling at 400 km/s in the solar wind to reach the orbit of Jupiter,
as depicted here. In reality the surface becomes increasingly
distorted because of variations in the solar wind speed along the
surface and other dynamic effects operating in the interplanetary
medium.

The shape of the current sheet usually evolves slowly - over months -
as the large-scale pattern of the Sun's field changes in response to
the emergence and decay of solar active regions. Coronal mass
ejections often disrupt the background pattern temporarily, but
sometimes the changes are permanent.

During most of the solar cycle the current sheet is basically a tilted
dipole with varying degrees of quadrupole distortion. Near solar
maximum the dipole decays leaving a much more complicated structure.
This picture shows the heliospheric current sheet as it might appear
during the rising phase of the cycle, when the dipole and quadrupole
components are balanced; at this point the neutral line at the base of
the sheet resembles the seam on a baseball.

Prof. John M. Wilcox was one of the discoverers of the heliospheric
current sheet and did much to develop our understanding of it during the
1960s and 1970s. He worked with NASA artist Werner Heil to create this
picture. The shape for this solar rotation was based on Ken Schatten's
Current Sheet Magnetic Model for the Solar Corona
(Cosmic Electrodynamics, 2, 232-245, 1971).
An early 3D rendering of the HCS appeared in a 1976 paper by L. Svalgaard
and J.M. Wilcox in Nature (Vol 262, page 766).